Former Interior Secretary Sally Jewell took sharp aim Wednesday at her successor's national monument "review," calling moves to shrink Bears Ears and other designations illegal gestures that put President Donald Trump on "the wrong side of history" and pose a major threat to public lands.

Speaking early Wednesday at the Outdoor Retailers final trade show in Salt Lake City, Jewell accused Trump of treating monuments like "contestants on a game show" and Interior Secretary Ryan Zinke of offending the conservation legacy of Teddy Roosevelt that the former Montana lawmaker is fond of invoking.

"The president does not have the authority to change monuments, only Congress does, and Congress has modified monuments…. If the president acts unilaterally to make changes, it will immediately be challenged in court," Jewell told outdoor industry leaders packed into a ballroom at a City Creek hotel.

"[T]his review is deeply unpopular and out of step with what the vast majority of Americans want," Jewell continued, referring to the 2.7 million comments submitted to Interior regarding the monument review. "If [Trump] acts to revoke, he will go down as one of the most anti-conservation presidents in the history of this nation. Our parks and monuments are part of what makes this nation great."

The Interior Department did not immediately respond to a request for comment on Jewell's remarks, made during what was her first major appearance since leaving office in January.

Jewell said she was hesitant to chastise her successor so early in his tenure, given Trump's push to undo much of the President Obama's conservation agenda.

"We have very real threats facing the public lands we love so much, and so I intend to speak up thoughtfully, respectful and factually," she said.

REI's former chief executive, Jewell has returned to Seattle after serving President Barack Obama's second-term Interior boss. Her 10,000-mile journey home with husband Warren last spring passed though 60 wildlife refuges, parks, monuments, including Utah's Bears Ears and Grand Staircase national monuments. She plans to begin a fellowship this fall at Harvard's John F. Kennedy School of Government.

Her remarks Wednesday were part of a breakfast panel hosted by the Outdoor Industry Association (OIA), which led the charge to pull the twice-a-year OR trade show from Salt Lake City in response to Utah's stances on public lands, which industry leaders say are antithetical to not only their interests but the economic well-being of the West.

Outdoor leaders have long argued with Utah politicians over wilderness and roads, but it was the state's push to revoke Bears Ears that led the industry to find a new home for the massive show in Denver.

At the urging of Utah Sen. Orrin Hatch, Trump in April ordered Zinke to review 27 large monument designated under the Antiquities Act since 1996. The secretary has since recommended drastically "right sizing" Bears Ears and will release final details in late August, along with recommendations for other monuments.

New polling commissioned by The Salt Lake Tribune shows are Utahns evenly split over the size of Bears Ears, which covers 1.3 million acres in San Juan County. Forty-two percent agree with Zinke the monument is too big, 39 percent disagree and 19 percent don't know.

But in her opening remarks OIA executive director Amy Robert struck a conciliatory tone, thanking Salt Lake City and Utah for hosting the twice-a-year show for the past 22 ears.

"You gave us a place for people to gather, share ideas and help make their businesses move forward," Roberts said. "This isn't the end of our decades-long partnership. It's an evolution."

Her group is organizing a march and rally at the Utah Capitol Thursday afternoon to celebrate public lands. While deeply critical of Utah's call to transfer public lands to the state, OIA appears to be keeping its message positive and gracious, as illustrated by a newly announced donation from the group to Parks4Kids Utah, an organization that connects children with the outdoors.

Roberts and Jewell shared the podium with Montana's Democratic Gov. Steve Bullock, who said access to federally managed forests, deserts, mountains and streams are Westerners' "birth right."

"Public lands are a great equalizer," Bullock said. "You don't need to be a millionaire from Deer Valley, Jackson Hole or Big Sky to hike on those lands or camp in your favorite parks.

"While these lands may be equally owned," he said, "the economics of what they generate belong to us."

Later Wednesday the Montana governor presented state-by-state economic data that show the outdoor industry supports 7.6 million jobs and $887 billion in consumer spending, more than what Americans spend on pharmaceuticals and fuel. Utah's share of that is $12.3 billion and 110,000 jobs.

"Investing in our lands will pay off economically for decades to come and transferring them out of public hands would be damn foolish," he said. "Outdoor recreation has become of our larges economic sectors, representing the life blood for thousands of communities, providing livelihoods for millions of American workers."

Jewell recalled the shrill headlines and punditry that followed monument designations a century ago, predicting the demise of local communities.

"A monstrous crime against development and advancement. It leads me to wonder if Washington has gone crazy catering to conservation faddists." This is how the Alaska Daily Empire opined on the Glacier Bay monument designation in 1924. Last year half a million visited this park, leaving $112 million.

"Conserving these places appeared to many as a threat to their way of life. It's hard to let go of the known if we don't know what's coming, but now we have the benefit of 150 years of history," Jewell said. "Today these parks stand as crown jewels of our nation's public lands and anchors for local economies."